The present invention relates to spinal implants, and in particular to a graftless spinal implant that employs a bioactive coating such as hydroxyapatite to promote fixation of the implant to adjacent bony surfaces.
U.S. Pat. No. 6,241,769 entitled “Implant for Spinal Fusion” and U.S. Pat. No. 6,096,080 entitled “Apparatus for Spinal Fusion Using Implanted Devices” disclose spinal replacement devices. Both patents discuss in detail the problems associated with the prior art devices.
The devices disclosed in U.S. Pat. Nos. 6,241,769 and 6,096,080, each hereby incorporated by reference, utilize a central graft space for promoting the long-term fixation onto adjacent bony surfaces. The device can be fabricated from human bone allograft material of bone substitute material such as coral or calcium phosphate. A problem with the devices disclosed in these patents is that they require a bone graft, and the failure rate of these types of devices is fairly high. In addition, there is an unacceptably high rate of morbidity (e.g., 30%).
Therefore, there is a need for a spinal implant device that does not utilize a bone graft in an attempt to facilitate fixation of the implant device to adjacent vertebral bony surfaces, and thereby stabilize the spinal motion segment.